Using system dynamics to model water-reallocation

Abstract

Improving the efficiency of water allocation has long been recognised as a key problem for the water resources management decision-makers. However, assessing the efficacy of management decision is difficult due to the complexity and interconnectivity of water resource systems. For this reason, it is vital that robust modelling approaches are employed to deal with the feedback loops inherent in the water resource systems. Whilst many studies have applied modelling to various aspects of water resource management, little attention has been given to innovations in modelling approaches to deal with the modelling challenges associated with improving decision-making.The aim of this study is to apply a System Dynamics modelling approach to improve the efficiency of water allocation incorporating a myriad of irrigation system constraints. The system dynamic approach allows the different system components to be organised as a collection of discrete objects that incorporate data, structure and function to generate complex system behaviour. Through the application of a system dynamic approach, a robust model (named the Economical Reallocating Water Model (ERWM)) was developed which was used to examine the options of re-allocating water resources that minimize the water cost all over an irrigated agricultural area. The ERWM incorporated a wide range of complexities likely to be encountered in water resource management: surface and ground water sources, water trading between sources, system constraint such as maximum ground water pumping, rates, maximum A. Elmahdi ( ) CSIRO, land and water, Springer 4 Environmentalist (2007) 27:3-12 possible trading volumes and differential water resource prices. Two hypothetical systems have been presented here as an example. The results show that the System Dynamics approach has a significant advantages in estimating and assessing the outcomes of alternative water management strategies through time and space.

Possibility of Inventory Pooling in China’s public hospital and appraisal about its performance

“…Vensim modeling language is a rich and readable way of representing dynamic systems and can provide a programming environment for model development and help solve problems that would be hard to address mathematically [14].…”

Modeling the system dynamics for nutrient removal in an innovative septic tank media filter

“…System dynamics modeling, known as a well-established methodology specially for studying and managing complex feedback systems, has been used to address a variety of environmental/ecological studies including environmental impact assessment of coalfields [23], tree growth [19], lake eutrophication assessment [22], wetland study for metals [25], groundwater recharge [1], pesticide control [11], water reallocation [10], wastewater treatment [16], river pollution control [8], lake watershed management [13], lake toxics mass balance assessment [12], and solid waste management [9].…”

Water resources planning and management based on system dynamics: a case study of Yulin city

“…Usually, an SDM project consists of the following phases: problem definition, system conceptualization, model formulation, model evaluation/testing, policy analysis and implementation (Karavezyris et al 2002;Xu et al 2002;Ahmad and Simonovic 2004;Elmahdi et al 2007;Zhang et al 2008). It is important to determine the positive and negative relationships between variables, feedback loops, system archetypes and delays.…”

“…They provide a set of graphical objects with their mathematical functions for easy representation of the system structure and the development of computer code. Simulation models can be easily and quickly developed using these software tools (Guo et al 2001;Sun et al 2002;Xu et al 2002;Ahmad and Simonovic 2004;Elmahdi et al 2007;Zhang et al 2008). The following equations show the basic mathematical form of the Vensim modelling language.…”

“…This influence is considered as positive (?) if an initial change is amplified in the same direction as all components are traced through the loop, or negative (-) if an increase in one element causes a decrease in another (Karavezyris et al 2002;Xu et al 2002;Yu et al 2003;Ahmad and Simonovic 2004;Zhang 2005;Elmahdi et al 2007;Zhang et al 2008). The hypotheses about these influences are based on literature studies as well as works previously carried out at our research unit.…”